I don't know about other admins here, but normally, I can have over a dozen tabs open in my Firefox web browser on my iMac. One tab which I do NOT have constantly open is the AdminCP tab. As a result, unless I go there, I may not realize that there are new users waiting to be verified and approved. As such, they may be waiting for days before I discover that they need to be approved.
I don't know if there is a setting for this or not, but if not, it would be nice if there was a option to send the Admin an email whenever a new user signs up. You could set it up with a few options such as these:
Send email to Admin immediately when new user registers
Send email to Admin every 6 hours when new user registers
Send email to Admin every 12 hours when new user registers
Send email to Admin every 24 hours when new user registers
Personally, I check my email frequently throughout the day, so this kind of notification would immediately attract my attention, even if I forget to visit the AdminCP for a few days.
One thing we don't want to do is to keep our new, potential users waiting, because they might lose interest and slip off the hook.